Waterstop with provision for flexing



March 9, 1965 s. D. BRADLEY wA'rERsToP wrm PRovIsIoN Fox pLExmc 2 Sheets-Sheet 1 Filed April 25, 1960 SrsPHg-N BY WILSON, Lem/lsf MEAE,

ATTORNEYS March 9, 1965 s. n. BRADLEY 3,172,237

wA'IERsIoP wIIx-x PROVISION Foa FLEXING Filed April 25, 1960 2 sheets-sheet 2 1 5 INVENToR.

STEPHEN D. BRADLEY WILSON, Lewis f Nic/2A: ATTORNEYS Unted States Patent O p A A 3,172,237 WATERSTOP WITH PRVISION FOR FLEXING Stephen D. Bradley, Grosse Pointe Farms, Mich., assigner to Detroit Macoid Corporation, Detroit, Mich., a corporation of Michigan Filed Apr. 25, 1960, Ser. No. 24,315 4 Claims. (Cl. 50-71) The present invention relates to a waterstop for use in forming a Huid-tight expansion, contraction, and shear joint between adjacent concrete panels. The waterstop of the present invention is particularly adapted and deconcrete with one halt of it embedded in each panel of concrete. Some such waterstops have included the provision of a tubular central section extending longitudinally of the strip to provide for expansion and contraction between the adjacent panels of concrete. However, it has been found that as the poured concrete panels dry and shrink the embedded anges of such waterstops tend to pull away from the surrounding concrete because at this stage the concrete has very little strength and the prior art devices do not provide for suilicient flexibility of the waterstop to compensate for this lack of strength of the drying concrete. Thus, the llanges ot prior waterstops are often loosened even before the concrete panels are completely set.

Another problem which has resulted from the use of prior waterstop devices is that with repeated expansion and contraction ot the adjacent panels of concrete the embedded iianges of the waterstop loosen sufficiently to allow water to seep around the anges and thus defeat the purpose of the Waterstop.

A further problem encountered with prior yart waterstops is the lack of provision for shearing movement, i.e., relative lateral motion between the sidewalls and door of a building in geographical areas subject to earthquakes, or relative lateral motion between the ioor and sidewalls of structures resulting from unequal exposure to extremes of temperature. The latter situation exists, for example, in the case of a concrete silo or similar storage tank wherein expansion and contraction of the concrete sidewalls as a result of changes in the ambient temperature result in expansion and contraction of the diameter of the silo or tank but no such change in the floor or footings on which the walls rest.

Additionally, the prior art devices do not adequately support the edges of the concrete panels in which they are embedded with the result that these edges tend to chip and crack oli.

Accordingly, it is one object of the present invention to provide a waterstop for positioning across the junction of adjacent panels of concrete which waterstop has provision for llexing of a central portion thereof during the drying and shrinking ot the concrete thereby -avoiding any loosening of the portions of the waterstop embedded in the panels.

Another object of the present invention is to provide such a waterstop which utilizes the pressure of water tending to torce its way between the junction of adjacent concrete panels to increase the effective barrier provided by the waterstop.

A further object of the present invention is to provide such a waterstop which will absorb forces in shear thereby compensating for relative lateral movement between the adjacent panels of concrete.

A further object of the present invention is to provide such a waterstop having a relatively soft central longitudinal section and more rigid side flanges extending therefrom and embedded in the adjoining edges of concrete panels whereby the more rigid side anges assure that the edges of the concrete panels will be always rigidly supported and the comparative softness of the central section assures that it will stretch and contract to absorb expansion and contraction and sheer forces thereby eliminating stretching of the side anges which would otherwise result in a reduction of the cross-sectional area of the side flanges and consequent loosening of the anges in the surrounding concrete that would allow leakage of water around the anges.

A further object of the present invention is to provide novel means for supporting the waterstop of the present invention during the pouring of the concrete panels.

Other objects of this invention will appear in the following description aud appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

FIG. l is an end View of a waterstop embodying the present invention,

FIG. 2 is a perspective view of a portion of the waterstop of FIG. l showing particularly the bottom thereof,

FlG. 3 is a cross sectional View through the junction of adjacent concrete panels showing the waterstop of the present invention in position,

FIG. 4 is a cross sectional view similar to that of FIG. 3,

FIG. 5 is a view of conventional forms for pouring a concrete highway ribbon or the like with portions broken away to show the waterstop of the present invention positioned therein, and

FIG. 6 is a vertical sectional view of a footing showing the waterstop of the present invention positioned therein.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings,

'since the invention is capable of other embodiments and of beino practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

In the drawings, there is shown a waterstop 1t) comprising a central longitudinal section 12, which is in cross-section an inverted U-shape, and longitudinal side ilanges 14 extending on each side ofthe central section and integral therewith.

The side anges are provided with a plurality of longitudinally extending ribs 16 to aid in the retention of the flanges within the concrete panels. As can be clearly seen in FIGS. 1 and 2, the4 inner sides 16a of the ribs, i.e., the sides facing the center of the waterstop, drop abruptly and meet the flange perpendicularly while the other or outer sides 16b taper downwardly and outwardly and meet the flange lat an acute angle. The abrupt inner sides of the ribs serve to anchor the flange securely in the concrete and provide optimum resistance to lateral forces tending to pull the ange out of the concrete. At the same time, the outward and downward taper of the outer sides serves to buttress the ribs against such forces.

Referring specically to FIGS. 1 and 2 of the drawings it will be noted that a rip membrane 18 extends across the bottom of the U-shaped central portion. This membrane is provided with a plurality of apertures 20 therethrough for a purpose that will be described hereinafter. These apertures are about the size of pinholes and are spaced about a foot apart along the length of the rip membrane.

The waterstop of the present invention may conveniently be extruded using a polyvinylchloride or similar thermoplastic material. The material utilized for the central U-shaped section 12 is significantly softer than that utilized for the side flanges 14, the difference between the two being preferably 15 to 20 points on the Durometer A scale. I have found it most suitable to utilize for the central U-shaped section a material having a Durometer A scale within the range of approximately 60 to 80 in combination with side flange material having a Durometer A scale within the range of approximately 85 to 95 while maintaining the spread between the two of from 15 to 20 points. The two materials must, of course, be compatible so that as the waterstop is being extruded the union of the side flanges and the central section will be such as to avoid any possibility of separation when the waterstop is in use. It is well known in the art of extrusion of thermoplastic materials that compatible materials having different physical characteristics may be utilized for different areas of an extruded section. The extrusion of the present invention as an integral section utilizing softer material for the central section therefore presents no problem to those skilled in the art.

Referring to FIG. 3 of the drawings the waterstop embodying the present invention is shown in position across the junction of adjacent panels of concrete 22 that abut in edge-to-edge fashion as illustrative of building walls such as basement walls, and of concrete highway construction and bridge roadway construction. As illustrated in FIG. 3 the adjacent concrete panels have dried and contracted to the point where there is a significant separation of their abutting edges.

Referring to FIG. of the drawings there is illustrated a novel means for supporting the waterstop of the present invention in position in the forms into which the concrete panels are poured. There is illustrated the conventional side forms 26 defining the longitudinal margins of a roadway ribbon. Extending transversely between the side forms at conventional intervals are the cross members 2S that serve to divide the ribbon into a series of panels. In order to accommodate the waterstop of the present invention the cross-members are provided with a longitudinal slot 30 in which the waterstop is positioned. To hold the flange 14 in its proper position while the concrete is being poured into the form there are provided the support members 32. These support members may be conveniently formed of stiff wire and comprise an anchoring end 32a which is sharpened so it may be driven into the cross member 28, an intermediate portion 3211 extending angularly from the anchoring end and a terminal portion 32C bent back upon itself to form a U-shaped grip to straddle the edge of the flange of the waterstop. The supports prevent the flange from being knocked out of position as the concrete is pouring into the form. It will be noted that the supports are positioned on the same side of the waterstop as the U-shaped central section. This is for a purpose which will b'e hereinafter described.

Referring to FIG. 6 of the drawings there is illustrated a waterstop of the present invention embedded in a footing such as the footing for a building wall, a silo or tank, or a reservoir or pool. The usual conventional trench 34 is dug into the ground and the forms 36 are positioned along the top edges of the trench so that the footing will extend above the trench the desired amount. The wall which is to be poured on top of the footing after the footing dries is illustrated by phantom lines. Immediately after the concrete is poured into the footing form and leveled even with the top of the form the waterstop is placed in position in the footing. This is accomplished by forcing a groove lin the top of the footing with a board or metal plate in a conventional manner and into this groove one of the side flanges of the waterstop is seated. The' concrete is then packed firmly around the flange and,- since it is still in a fluid state will additionally pack firmly around the flange by its own natural flowing and settling. In order to assure that the top flange, as illustrated in FIG. 6, remains in proper position while the wall is being poured on top of the footing and to additionally stiffen the waterstop transversely while it is being forced into the footing I provide the novel supports 38 spaced at intervals along the length of the waterstop. These supports are generally rl-shaped and roughly similar to a double one of the supports just described as being illustrated in FIG. 5. The terminal portions 38C straddle each edge of the waterstop and the intermediate portion 38h connects the terminal portions. Thus, the supports hold the waterstop rigidly in position with the side flanges aligned and prevent the upper flange from being knocked over as the concrete is poured for the walls. The supports are placed in position on the waterstop while the waterstop is being forced into the top of the footing as just described. Thus,` when the footing has dried the bottom portion of the support 38 and the bottom flange of the waterstop are rigidly retained therein. The supports 38 are again positioned on the same side of the waterstop as the U-shaped central section of the waterstop as in FIG. 5.

While the concrete is being poured into the forms, the rip membrane 18 assures that none of the concrete will be forced into the inside of the U-shaped central portion of the waterstop. The apertures 20 are not sufficiently large to permit -the passage of concrete therethrough dur ing the pouring operation. As the concrete dries and accordingly shrinks, the softer central section of the water stop compensates for `this shrinkage. Since the central section is softer than the side flanges it will yield and stretch to compensate for the shrinkage of the concrete without exerting any significant force on the side flanges 14. Thus, the side flanges will not be pulled loose from the weak concrete during the setting and curing of the concrete. Y

Referring again to FIG. 3 of the drawings some of the' novel features of the present invention can be described. In ythis respect, taking the illustration of FIG. 3 as a porJ6 tion of the side Wall of a basement, `the cross section of FIG. 3 would be a horizontal cross section looking downd wardly from the top `of the wall. The inside of the basement Wall is thus toward the top, as viewed in FIG. 3, and the outside is toward the bottom. The adjacent panels of concrete 22 have :shrunk to the extent that the rip membrane 18 has been stretched and torn while the U-shaped central section 12 of the waterstop has also been deformed.

FIG. 4 illustrates 4the use of the pressure of the water tending to enter between the junction of the adjacent panels of concrete to increase the sealing effect of the waterstop of the present invention. Taking FIG. 4 to illustra-te a basement wall as just described in relation to FIG. 3, .the direction of the water attempting to enter the basement is illustrated by the arrow A. This water enters the interior of the U-shaped cen-tral section 12 of the waterstop thus causing it to balloon outwardly and sideways .against the edges of the concrete panels. No matter how carefully the waterstop is installed and the concrete poured ythere is always lthe possibility of pathways being present around the side flanges i4. Water following this tortuous path is indicated by the arrow B. The pressure of any water following the path B by the time it reaches the opposite side of the waterstop would be significantly less because of the tortuousness of the path and thc friction resisting its flow. Thus, the pressure of the water following the path B will always be significantly less than the water pressure A. Therefore, the central section l2 of the waterstop is forced against the adjoining edges of the concrete panels, for example along the line indicated by the letter C in FIG. 4, by the greater water pressure A :thus preventing the passage of the water which has followed the path B into the basement. The novel waterstop of the present invention is always installed with the bottom of the U-shaped central section facing the direction from which water will Itend to force its way through ithe junction between the adjacent panels of concrete. As just described in connection with FIGS. 3 and 4 this is from the bottom as viewed in those figures. FIG. 5 is the same condition since ground water will tend to force its way upwardly between the adjacent panels of the concrete highway ribbon. It can now therefore be seen why the wire supports 32 are -positioned on the same side of the waterstop as the U-shaped central section. Were these reversed from that illustrated in FIG. 5 the water would soon rust away the supports and an easy path part way around the side anges of the waterstop would result.

Referring to FIG. 6, it will be noted 4that the U-shaped central section of the waterstop and the support 38 are positioned to the same side of the waterstop, i.e., to the left as viewed in FIG. 6. Thus, assuming that FIG. 6 illustra-tes a footing for a basement wall with the basemerit wall sho-wn in phantom, the outside or ground is to the right and the water would tend to enter from this direction. Similarly, if the illustration of FIG. 6 is taken to be that of a concrete silo the inside of the silo is to the left with the ground water tending -to enter Ifrom the right. However, assuming that the illustration of FIG. 6 is that of a reservoir or swimming pool 4the inside is to the right and the outside to the left since the greater water pressure is from that stored within the structure and the water within the structure would tend to force outwardly between the adjacent concrete panels with a greater force than the ground water would be forcing inwardly. Here also it will be noted that the waterstop is positioned with the bottom of the U-shaped central section facing the direction .from which the greater water pressure Will be tending to force between the adjacent panels of concrete and the wire supports 3S are positioned on the opposite side so as `to avoid any possibility of the incoming water following the supports as a convenient path part way around the side flanges.

In the event that expansion and contraction of the adjacent panels of concrete has not been sufficient to tear the rip membrane 18, the apertures 20 provided therein, as illustrated especially in FIG. 2, then provide a safety feature for assuring that water can force its way into the interior of the U-shaped central section. As has pireviously been described the apertures are nothing more than pinholes so as to prevent the entry of concrete into the central section but will allow the passage of water therethrough in the event that the rip membrane 18 is still intact.

The waterstop of the present invention is particularly advantageous in bridging the gap that must be left where a concrete roadway joins a bridge roadway. In this environment, the illustration shown in FIG. 3 would represent in the left hand portion the roadway provided on the bridge and in the right hand portion the adjoining edge of highway pavement. The gap is even more pronounced than illustrated in FIG. 3 and is constantly open. Thus, the central section of the waterstop would constantly be exposed to extremes of climate. Because the waterstop of the present invention incorporates a relatively soft central section the central section still retains its flexibility even when subjected to extreme cold.

In the same environment just described a further advantage of the waterstop yof the present invention can be pointed out. As has previously been discussed, the side flanges 14 are formed of a relatively hard material. It will be noted from FIG. 3 that the inner extremity of the side flanges extends almost to the edge of the panel of concrete in which it is embedded. Where the gap between adjacent sections of concrete roadway is significant the edges of these sections tend to chip off if there is any weakness in the support thereof. With the waterstop constructed according to the present invention the section ofthe concrete panel immediately above the side anges is rigidly supported by the side flange. Were the side ange not formed of such a hard material it could easily be compressed and the embedding of the side ianges would in effect be undercutting the upper edge of the concrete panel and thus contributing to the chippingand cracking thereof. However, the strength and rigidity of the side flanges of the waterstop constructed according to the present invention avoids this problem.

As can be seen from the above description of the waterstop installed across the junction of adjacent panels of concrete, because the central section 12 is softer it yields first, i.e., stretches, and contracts to compensate for the contraction, expansion and relative lateral movement of the adjacent panels of concrete. This avoids stretching of the side flanges which would otherwise result were the central section and the side flanges made of material of the same Durometer scale. Because of this feature the size of the side flanges can be materially reduced thereby making it possible to use smaller waterstops than heretofore possible. This, of course, results in a significant saving because a smaller waterstop can be utilized to achieve the same results for which a much larger prior art waterstop Was necessary.

Having thus described my invention, I claim:

l. Ari elastomeric membrane positioned at a joint between adjacent cast concrete panels, including a central section bridging the joint between the panels and a pair of laterally projecting liaiiges integral with the central section and each ange being embedded in one of the panels, respectively, the center section and the flanges of said strip being formed of homogeneous, substantially uniform elastomeric material which is of different hardnesses with the center section being substantially softer and more readily distortable than the iianges in order to accommodate deformation and stretching thereof without disturbing the embedded flanges upon relative separation of the concrete panels to subject the membrane to a tensile load.

2. elastomeric membrane as defined in claim 1 wherein said center section is of a hardness on a Durometer A scale ranging from about 60 to about 80 and the anges are approximately 15 to 20 points higher on said Durometer A scale.

3. A waterstop to be positioned at a joint between adjacent cast concrete panels, the waterstop comprising, in cross-section, a central section for bridging the joint between the panels and a pair of laterally projecting anges integral with the central section and adapted to be imbedded in the panels, respectively, the central section being in the form of a hollow bulb lying substantially to oneside of a median plane to the anges and having a relatively thin rip-membrane lying substantially in the mean plane of the anges, the dimension in said mean plane dening the width of said waterstop, said water stop being of greater length than width and of greater width than height, said central section and said iianges being formed of compatible elastomeric material of substantially differing hardnesses, the .central section being substantially softer and more readily distortable than the anges in order to accommodate ready tearing of the rip-membrane and stretching and distortion of the` central portion after tearing without disturbing the relatively harder anges upon attempted relative separation of the panels when the waterstop is installed so that the central section bridges the panels in which said flanges are embedded.

4. A waterstop as defined in claim 3 wherein said central section including said rip-membrane is of a hardness on a Durometer A scale ranging from 60 to 80 and the flanges are of a hardness on a Durometer A scale ranging from to 95.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Atzenhofer 296-445 Sipe 50-346 X Rawlings 50-71 X De Whirst 94-18 Older 94-18 Gardner 50-346 Fischer 94-18 Robertson 94-18 Goodman 50--346 Bush 50--267 X Wey 50--346 Harza 50-346 8 FOREIGN PATENTS 775,558 57 Great Britain. 784,111 5 7 Great Britain. 568,764 1/59 Canada.

OTHER REFERENCES `ournal of the American Concrete Institute (a. pubication, pages 84-88, copy in Div. 33, Sept. 1955.

10 HENRY C. SUTHERLAND, Primary Examiner.

WILLIAM I. MUSHAKE, JACOB L. NACKENOFF,

Examiners. 

3. A WATERSTOP TO BE POSITIONED AT A JOINT BETWEEN ADJACENT CAST CONCRETE PANELS, THE WATERSTOP COMPRISING, IN CROSS-SECTION, A CENTRAL SECTION FOR BRIDGING THE JOINT BETWEEN THE PANELS AND A PAIR OF LATERALLY PROJECTING FLANGES INTEGRAL WITH THE CENTRAL SECTION AND ADAPTED TO BE IMBEDDED IN THE PANELS, RESPECTIVELY, THE CENTRAL SECTION BEING IN THE FORM OF A HOLLOW BULB LYING SUBSTANTIALLY TO ONE SIDE OF A MEDIAN PLANE TO THE FLANGES AND HAVING A RELATIVELY THIN RIP-MEMBRANE LYING SUBSTANTIALLY IN THE MEAN PLANE OF THE FLANGES, THE DIMENSION IN SAID MEAN PLANE DEFINING THE WIDTH OF SAID WATERSTOP, SAID WATER STOP BEING OF GREATER LENGTH THAN WIDTH AND OF GREATER WIDTH THAN HEIGHT, SAID CENTRAL SECTION AND SAID FLANGES BEING FORMED OF COMPATIBLE ELASTOMERIC MATERIAL OF SUBSTANTIALLY DIFFERING HARDNESSES, THE CENTRAL SECTION BEING SUBSTANTIALLY SOFTER AND MORE READILY DISTORTABLE THAN THE FLANGES IN ORDER TO ACCOMMODATE READY TEARING OF THE RIP-MEMBRANE AND STRETCHING AND DISTORTION OF THE CENTRAL PORTION AFTER TEARING WITHOUT DISTURBING THE RELATIVELY HARDER FLANGES UPON ATTEMPTED RELATIVE SEPARATION OF THE PANELS WHEN THE WATERSTOP IS INSTALLED SO THAT THE CENTRAL SECTION BRIDGES THE PANELS IN WHICH SAID FLANGES ARE EMBEDDED. 